This invention relates to the separation of an impurity from a liquid and, more particularly, to the separation of the solvent and solute of a solution by an induced phase change.
The separation of impurities from a liquid, as in the purification of water, is used in numerous industrial processes. Various systems exist for the purification of water. An exemplary case is the desalinization of sea water which is important for human health. The operation of desalination systems may involve the boiling and freezing of sea water, as well as the use of vacuum pumps in reducing the ambient pressure on the water to facilitate the production of water vapor. At present, two common methods for desalination are distillation and reverse osmosis, with a third process, freezing, not commercially in use.
The distillation process suffers from major drawbacks, particularly, high corrosion and high energy consumption. In the distillation process, the seat water must be heated and, accordingly, energy is consumed in large quantities and elaborate means must be used to recover as much heat as possible to keep the energy costs low. Also, since a hot brine solution is very corrosive, much care, pretreatment, and special materials need be used so as to avoid excessive maintenance requirements of the equipment.
With respect to systems utilizing the reverse osmosis process, such systems employ delicate membranes and suffer from clogging and deterioration of the membranes. To use such systems in the processing of liquids such as sea water with its relatively high degree of impurities requires specific pretreatment of the sea water. Also, with respect to systems utilizing the freezing process, the process involves the separation of brine from the pure ice product, or a separation of a refrigerant from the pure ice; such separation has yet to be accomplished on a commercial scale.
Thus, it is readily apparent that while systems employing various processes have been implemented for the purification of water and other liquids, such systems have failed to be fully satisfactory. Despite a long felt need and efforts to overcome problems which have beset these systems, such problems persist.